1. Field of the Invention
The invention relates to non-refillable or single use valves for pressurized systems.
2. Prior Art
Pressure tanks or other pressure containers are usually filled under carefully controlled conditions at a charging station and then distributed to various places for use. When empty it is intended that the containers be returned to the charging center for appropriate reuse or destruction in the case of single use containers. Unfortunately, the attractive economies of refilling containers at points of use or otherwise repressurizing them under less than carefully supervised conditions has resulted, in the less consequential cases, in the introduction of impurities or inferior refills and, in the more consequential cases, to injurious explosions. The reuse of pressure containers is highly objectionable for many reasons which relate to safety.
U.S. Pat. No. 3,704,813 teaches a fluid dispensing valve assembly having a body one end of which is formed for securement to a container. The body forms a conduit having only one through passage for filling and discharging fluid. There is a shut-off valve operable for controlling the flow of fluid through the passage. The shut-off valve has an externally accessible control. There is convertible means in the body comprising an initially inactive check valve initially in condition to accommodate the flow of fluid through the passage in both the filling and discharge directions. The check valve is convertible after an initial filling operation into an active check valve in the passage in series with the shut-off valve. The initially inactive check valve includes a movable valve member, a valve seat, means for biasing the valve member toward the valve seat, and detent means effective initially to prevent the cooperation of the valve member with the valve seat. The detent means is defeatable after an initial filling operation to enable the valve member to engage the seat. The check valve when active is operative to pass fluid only in the discharge direction. The check valve after being rendered active to obstruct the flow of fluid selectively in the filling direction is guarded against access from the exterior of the valve assembly when secured to a container for reopening the passage to the flow of fluid in the filling direction. Thereby a container equipped with the valve assembly can be evacuated and then filled with fluid in the initial condition of the valve assembly but is substantially non-refillable after conversion of the convertible means.
U.S. Pat. No. 3,985,332 teaches a non-refillable safety valve for a pressure container. The valve includes a housing, having a central bore, which provides communication between a port and the pressure container for charging and selective discharging the pressure container. The central bore has a lower portion that is narrower than the upper portion of the central bore. A hollow knob unit, having a central bore, is in threaded engagement with the outer wall of the housing. A core, having a central bore, is slidably mounted in the central bore of the housing. The upper end of the hollow knob unit is mounted on the core in a rotatable manner and in fixed longitudinal relationship with the core. A sealing member is slidably mounted in the lower end portion of the central bore of the core. The core contains end stop means for preventing movement of the sealing member below the lower end of the core. The sealing member engages the interface ledge formed by the lower upper portions of the central bore of the housing when the core is moved the maximum possible distance into the central bore of the core or when refill is attempted after discharge of the pressure container. The core contains at least one passageway located in the core outwards from the sealing member for communication between the central bore of the core and said upper portion of the central core, of the housing. An engagable stop means is positioned between the outer surface of the housing and the inner surface of the hollow knob unit in order to limit retrograde or outward movement of the core to a position whereby the sealing member still engages the interface ledge when refilling the pressure container. The engagable stop means engages after the pressure container has been filled and the sealing member, the core and the knob unit have been moved into sealing position.
U.S. Pat. No. 871,780 teaches a bottle having a neck provided with a passage and having a valve chamber at the inner end of the neck. A valve seat it formed in the chamber. There is a valve operable in the latter and provided with a compressible head adapted to close upon the seat and of greater diameter than the passage. The valve is elastic, and is inserted into the chamber of the bottle by forcing it in deformed shape down the neck of a bottle by means of a mechanism similar to a screw press. The bottle is inserted into the press box and the screw is used to force the deformed valve down the bottle neck. The valve mechanism is used to prevent fraudulent substitution of contents; use with pressurized fluids is not mentioned.
There is a need for a relatively simple and inexpensive valve which will allow normal filling of the pressure container under proper conditions, adequate sealing of the pressure container during nonuse, selective discharge of the pressure container, and effective prevention of improper and unauthorized refilling of the container.